1. Field of the Disclosure
This disclosure is directed to transformer topologies.
2. Related Art
In many applications, especially shipboard and aircraft applications, a high voltage direct current (DC) power is used to power motor controllers. Typically, a three phase alternating current (AC) voltage of 230 Volts RMS (root mean square) is generated in a ship or an aircraft. The generated AC voltage is applied to an auto transformer rectifier unit (ATRU) and rectified to generate a DC voltage of +/− 270 Volts. The rectified DC voltage from the ATRU is then used to power motor controllers. The output voltage of the motor controllers is limited by the rectified DC voltage of the ATRU. It is desirable to increase the voltage output of the motor controllers.
In order to increase the output voltage of the motor controllers, various approaches have been tried. One approach is to provide a higher input AC voltage. This approach has shortcoming because if the input AC voltage is increased, due to increased power, one has to increase the overall insulation level of the whole ship or aircraft. Increased input AC voltage may also lead to additional challenges like corona, high voltage spikes and component breakdown.
Another approach has been to cod a step-up autotransformer before the motor controller to get higher rectified output DC voltage or after the motor controller to get higher output AC voltage. Adding an additional step-up transformer before or after the motor controller adds additional heavy magnetic components the power generation system. Especially in a shipboard or aircraft applications, additional autotransformers may significantly add to the weight of the electrical subsystem and hence may not be desirable.
It is with these needs in mind the current disclosure arises.